This invention relates to the characterization of containers, and, more particularly, to a process and apparatus for determining the material of construction and the color of translucent and partially translucent containers.
In recent years, non-deposit containers for beverages and other goods have become widely used because their cost has been less than the cost of recycling and/or cleaning for reuse previously used deposit containers and bottles. One significant result of the widespread use of non-deposit containers has been increased litter in public places.
To combat litter and increase the amount of material that is recycled, several states have now enacted mandatory "deposit laws" that require the use of containers upon which a deposit must be paid. When the customer purchases a product in such a container, a container deposit, typically one to five cents, is added to the purchase price. After consumption of the product, the consumer can obtain a refund of the deposit by returning the empty container for recycling. The amount of the deposit may be adjusted to create an incentive for returning the container that is greater than the inconvenience in doing so.
For the system of laws and incentives which require or encourage recycling to work properly, the scrap sales value of the recycled material must be sufficiently greater than the cost of recycling so that the recycling activity is profitable. Some materials which are candidates for recycling, such as aluminum, have an inherently high scrap value and have found widespread industry acceptance for recycling. Other scrap materials, for example glass and plastics such as polyethylene terephthalate (PET), have such a low scrap value that it is difficult for the value of the recycled material to exceed the costs of recycling.
One approach to improving the economics of recycling is to reduce its cost, particularly the cost of labor to receive containers and pay the proper refund. Some groups and individuals, such as retailers, have opposed mandatory deposit laws because, they argued, the high labor costs of processing recycled material makes recycling uneconomic, particularly for low scrap value materials, such as glass and PET. To reduce the labor costs, various machines that accept material for recycling and issue deposit refunds have been proposed, and some have been placed into service. Such machines do achieve their objective of reduced labor cost.
Another approach to improving the economics of recycling is to increase the scrap value of the recycled material. One method for increasing the scrap value is to segregate the returned material into groups, the value of which is greater compared to that of unsegregated material. For example, the value of glass and PET, per pound, is greater when the two have been segregated than when they are mixed together. Carrying the example further, the value of glass (or PET) that has been segregated by color (for example, clear, amber, or green) is greater than the value of glass that is mixed together.
In the past, the segregation of returned containers into classes has been labor intensive, so that the labor to perform the sorting may cost more than the increase in resale value of the segregated material. It would be highly desirable to provide a device that can perform the segregation of materials into such groups quickly and inexpensively, so that the cost of the sorting process is less than the enhancement in value obtained through sorting. It would be particularly desirable to provide such a sorting device that could be utilized at the point of return of the recycled material, because the person charged with recycling (typically the retailer) would enjoy the enhancement in profit arising from its use. It is expected that such an approach would greatly increase industry support for recycling glass and PET.
There are few available apparatuses and processes for grading and sorting containers by material of construction and color. U.S. Pat. No. 4,919,534 describes such an apparatus and process wherein polarized light of at least two wavelengths is passed through a container. Portions of the transmitted beam are analyzed by parallel and cross polarizers, the intensities of the analyzed beams are measured, and the sum and difference of the analyzed beams are determined to yield information concerning the color and composition of the container. While the apparatus and method of U.S. Pat. No. 4,919,534 proved useful in some applications, such as in a laboratory environment, the use of two wavelengths of light proved impractical in others, such as in an uncontrolled environment. Moreover, the apparatus and method of U.S. Pat. No. 4,919,534 proved to be "blind" to some colors of containers.
Apparatuses and processes for grading and sorting containers by material of construction and color should meet the requirements discussed previously, and also be operable with containers that are less than ideal, such as those which are dirty or have labels. The present invention fulfills this need, and further provides related advantages as will be apparent to those skilled in the art after reading this specification and the accompanying drawings.